The present invention relates to speakers, in particular loudspeakers, and the speaker's enclosure configuration, and to a method for manufacturing the same.
Loudspeakers reproduce original, recorded signals. The performance of a loudspeaker is evaluated its ability to faithfully reproduce the original source wave form, namely a degree of match between the profile (frequency and amplitude profile) of a loudspeaker's output signal and the original source signal.
One of the main parts of a speaker (e.g. loudspeaker) affecting the loudspeaker performance is a speaker enclosure (e.g. cabinet), in which an electroacoustic transducer(s) (hereinafter also referred to interchangeably as speaker driver(s)) and associated electronic hardware are mounted. Speaker enclosures may be of a simple box-like design, or may be a complex cabinet, including composite materials, internal baffles, horns, ports and acoustic treatment (absorption, diffusion, stuffing, insulation).
To improve the performance of a speaker, it is desired for the enclosure/cabinet of a speaker to be substantially neutral with respect to the signal being reproduced, such that the system's resonance(s) caused by the signal interaction with and propagation in the enclosure is/are reduced/minimized.
Also, the loudspeaker should be configured with reduced backwave distortion effects. The backwave distortion is induced by interaction between sound waves generated by the rearward-facing surface of a diaphragm with sound waves generated at the front of the driver. This is because interaction of the forward- and backward-generated sounds (which are out of phase with each other) in the listening space creates a distortion of the original signal to be reproduced. Accordingly the forward and backward sound waves arrive at the listener's position at slightly different times, thereby resulting in loss of detail and clarity of the reproduced sound and damage to the stereo image and sound stage. Various techniques have been developed to solve this problem. A common approach for most, if not all, of these techniques, is based on filling the speaker enclosure by foam or other fibrous or porous material(s) to absorb backward-generated sounds. This, however, reduces the quality of the output signal, e g making the system sound “muffled”. Also, acoustic absorption is not equally effective at all frequencies and is amplitude dependent. This means that not all the frequencies are attenuated uniformly, and the louder the speaker plays, the less effective it becomes (since more absorption is required to achieve a desired result).